[scudo] Limit stack depot size on Trusty

The stack depot uses several megabytes of memory
which is a lot for Trusty.

Reviewed By: Chia-hungDuan

Differential Revision: https://reviews.llvm.org/D156392

Author: ahomescu

compiler-rt/lib/scudo/standalone/platform.h

@@ -63,6 +63,12 @@
 #define SCUDO_CAN_USE_MTE (SCUDO_LINUX || SCUDO_TRUSTY)
 #endif
 
+// Use smaller table sizes for fuzzing in order to reduce input size.
+// Trusty just has less available memory.
+#ifndef SCUDO_SMALL_STACK_DEPOT
+#define SCUDO_SMALL_STACK_DEPOT (SCUDO_FUZZ || SCUDO_TRUSTY)
+#endif
+
 #ifndef SCUDO_MIN_ALIGNMENT_LOG
 // We force malloc-type functions to be aligned to std::max_align_t, but there
 // is no reason why the minimum alignment for all other functions can't be 8

compiler-rt/lib/scudo/standalone/stack_depot.h

@@ -62,8 +62,7 @@ class StackDepot {
   // This is achieved by re-checking the hash of the stack trace before
   // returning the trace.
 
-#ifdef SCUDO_FUZZ
-  // Use smaller table sizes for fuzzing in order to reduce input size.
+#if SCUDO_SMALL_STACK_DEPOT
   static const uptr TabBits = 4;
 #else
   static const uptr TabBits = 16;
@@ -72,7 +71,7 @@ class StackDepot {
   static const uptr TabMask = TabSize - 1;
   atomic_u32 Tab[TabSize] = {};
 
-#ifdef SCUDO_FUZZ
+#if SCUDO_SMALL_STACK_DEPOT
   static const uptr RingBits = 4;
 #else
   static const uptr RingBits = 19;